| Message ID | trinity-4fa6f356-db34-4fbf-8eaf-de069b33adfd-1609517673193@3c-app-gmx-bs09 |
|---|---|
| State | New |
| Headers | show |
| Series | PR fortran/96381 - invalid read in gfc_find_derived_vtab | expand |
Hi Harald, It looks good to me - OK for master and backporting. Thanks Paul On Fri, 1 Jan 2021 at 16:14, Harald Anlauf via Fortran <fortran@gcc.gnu.org> wrote: > Dear all, > > happy New Year! > > The testcase committed with the fix for PR93337 uncovered a latent issue > with an invalid read that was discovered with an ASAN instrumented compiler > but which could also be verified by running f951 under valgrind. > > According to my gdb sessions the invalid read happens when processing a > statement that refers to a rejected declaration of a CLASS instance. > We simply should not try to look up the vtab entry in such cases. > > All variations of the testcase gfortran.dg/pr93337.f90 that I tried on > x86_64-pc-linux-gnu with the patch below appeared to behave clean running > f951 under valgrind. > > Regtested on x86_64-pc-linux-gnu. > > OK for master? Since the fix for PR93337 was applied to 9/10/11, I intend > to backport after suitable waiting time. > > Thanks, > Harald > > > PR fortran/96381 - invalid read in gfc_find_derived_vtab > > An invalid declaration of a CLASS instance can lead to an internal state > with inconsistent attributes during parsing that needs to be handled with > sufficient care when processing subsequent statements. Avoid a lookup of > the vtab entry for such cases. > > gcc/fortran/ChangeLog: > > * class.c (gfc_find_vtab): Add check on attribute is_class. > >
diff --git a/gcc/fortran/class.c b/gcc/fortran/class.c index 5677d920239..783e4c7354b 100644 --- a/gcc/fortran/class.c +++ b/gcc/fortran/class.c @@ -2906,7 +2906,9 @@ gfc_find_vtab (gfc_typespec *ts) case BT_DERIVED: return gfc_find_derived_vtab (ts->u.derived); case BT_CLASS: - if (ts->u.derived->components && ts->u.derived->components->ts.u.derived) + if (ts->u.derived->attr.is_class + && ts->u.derived->components + && ts->u.derived->components->ts.u.derived) return gfc_find_derived_vtab (ts->u.derived->components->ts.u.derived); else return NULL;